This invention relates to electrical coupler devices operable at microwave frequencies and more particularly to improved wideband short slot couplers.
Hybrid couplers are widely used in microwave circuits for coupling a portion of the electromagnetic energy in one waveguide to another waveguide. In some cases, the coupling ratio is one-half so as to produce an equal split of the power among the two waveguides. In other cases, a smaller amount of the power such as one-quarter or one-tenth of the power may be coupled from one waveguide to the second waveguide. In a common form of coupler, known as a hybrid coupler, the two waveguides are brought contiguous to each other and in parallel relationship so as to share a common wall. An aperture or slot in the common wall provides for the coupling of the electromagnetic energy.
While such couplers operate satisfactorily over relatively narrow frequency bandwidths, for example, in the range of 5-15% bandwidths for 3 dB couplers in the X-band range, performance over relatively wide bandwidths has been unsatisfactory.
It would therefore represent an advance in the art to provide a wideband, compact hybrid coupler operable at microwave frequencies.